1. Field of the Invention
The present invention relates generally to the field of contents indicators for containers, and more specifically to an indicator that designates the status of the contents of refrigerant storage tanks.
2. Description of the Prior Art
Refrigerants, such as R502, R12, and R22, are commonly stored under pressure in storage tanks. Persons responsible for maintaining such tanks need to communicate among themselves as to the status of the contents of the tanks as well as the status of the tanks themselves. The status of the tank can include several possibilities. There may be one of several different kinds of refrigerant in the tanks. The stored refrigerants may have been recycled, reclaimed or recovered after use in an automobile air conditioner, commercial walk-in freezer, or other refrigeration system. A refrigerant storage tank may be under vacuum. After a tank has been emptied of refrigerant, nitrogen is introduced into the tank to prevent moisture condensation inside the tank. A storage tank may have a leaky or defective pressure valve that requires repair or replacement.
Prior to my invention, indication of the status of the contents of refrigerant storage tanks, and of the need for repair or replacement of storage tank valves, has been haphazard: one or more handwritten or typed messages would be attached to or written onto storage tanks relating information regarding the type and status of refrigerants and/or regarding defective valves.
Contents indicators for containers other than refrigerant storage tanks are known in the prior art. Barton et al., U.S. Pat. No. 3,903,837 (Sep. 9, 1975), disclosed a dial indicator device for attachment to a storage bin or box, in which various items are stored, having a base member containing a plurality of indicia on the outer face thereof for indicating the contents of the bin or box, and having a rotatable cover dial with a window within the face of the dial for selectively exposing the indicia to indicate the status of the item(s) within a particular box or bin. The indicia might indicate, for example, "order" or "on order," thereby assisting in inventory control of the stored items.
B. E. Giebel U.S. Pat. No. 3,180,310 (Apr. 27, 1965), disclosed the combination of a paperboard container and apparatus for indicating the contents of said container, wherein an outer end wall panel of the container had a generally triangular opening and an annular disk was rotatably mounted on an axle just below the opening. The annular disk was provided with a plurality of indicia visible through the opening of the outer end wall panel, each indicia occupying a sector and identifying a possible content of the container--e.g., bottles carrying various ingredients.
There remains a need for a device to indicate the status of refrigerant storage tanks whereby the nature, history and intended disposition of the contents of the tanks may be easily ascertained.